DRE STUDY GUIDE 7: SESSION 24 - DRUG COMBINATIONS| COMPLETE QUESTIONS AND ANSWERS 2025/2026 LATEST UPDATE

DRE STUDY GUIDE 7: SESSION 24 - DRUG COMBINATIONS| COMPLETE QUESTIONS AND
ANSWERS 2025/2026 LATEST UPDATE




Common Polydrug combinations • Cocaine and Cannabis

• Cocaine and Heroin

• PCP and Cannabis

• Alcohol and practically anything else




What are the four effects of drug combinations? • Null Effect

• Overlapping Effect

• Additive Effect

• Antagonistic Effect




What is the Null Effect? If neither drug affects a particular indicator of impairment, their
combination also will not affect that indicator.




No action + No action = No action




What are some examples of the Null Effect: • Narcotic Analgesic & Cannabis (HGN)

- Neither drug affects HGN

- The combination would not result in HGN being present

, • Dissociative Anesthetic & Cannabis (RTL)

- Neither drug affects reaction to light



• CNS Depressant & Cannabis (Body Temp)

- Neither a CNS Depressant nor Cannabis usually affects body temperature

- The combination of the two leaves body temperature in the DRE average range




What is the Overlapping Effect? Two drugs produce an Overlapping Effect if One if them
AFFECTS the indicator, but the other does not. Action + No action = Action




What are some examples of the Overlapping Effect? • CNS Stimulants & Dissociative
Anesthetics (Pupil Size):

- CNS Stimulants dilate pupils, Dissociative Anesthetics do not affect pupil size

- Therefore, pupils should be dilated




• CNS Depressants & Narcotic Analgesics (HGN):

- A CNS Depressant will cause HGN, but a Narcotic Analgesic will not cause HGN

- A person under the combined influence of a CNS Depressant and a Narcotic Analgesic will
usually have HGN




• Dissociative Anesthetics & CNS Depressants (Body Temp):

- Dissociative Anesthetics cause an elevated temperature